In Japan, exhaust emission regulations for diesel vehicles have been tightened since 1993, in view of the environmental destruction by toxic substances emitted from diesel engines. In other words, a short-term regulation, a long-term regulation, and a new short-term regulation have been introduced. Furthermore, a new long-term regulation to be the most stringent emission standard in the world was introduced in 2005. Furthermore, the “Automotive NOx and PM Law” and the like are in operation in specified areas. In this manner, Japan has tackled the reduction of black smoke such as nitrogen oxides (NOx) and particulate matter (PM: Particulate matter). However, vehicles before the regulation and vehicles with a long travel distance and a long use period are being used. Hence, diesel engine automobiles that emit a large amount of black smoke are still in use. It becomes a problem with the vehicles before the regulation and the vehicles with a long travel distance and a long use period that the emissions of black smoke, that is, particulate matter due to incomplete fuel combustion, have an adverse effect on the environment rather than nitrogen oxides. Also in the vehicle inspection standard, the emission amount of black smoke is the item to be checked strictly. Furthermore, the particulate matter emission standard one stage before the latest emission standard for new vehicles is defined for diesel trucks and buses in the one metropolis and three prefectures including Tokyo, Chiba, Saitama, and Kanagawa from Oct. 1, 2003. The passage operation of vehicles that do not meet the standard is banned in the areas.
In a combustion system for a diesel engine, fuel is injected into the heated compressed air to burn the spontaneously ignited fuel. On the other hand, in a combustion system for a gasoline engine, an air-fuel mixture of air and gasoline is compressed and ignited, and burns. The two combustion systems are greatly different. NOx in the exhaust gas of the diesel engine is generated under high temperature conditions of complete fuel combustion. Meanwhile, particulate matter (PM), mainly black smoke, is generated under incomplete fuel combustion. It is not easy to take a measure against the generation of black smoke and NOx in the exhaust gas of the diesel engine in the trade-off relationship.
Therefore, new vehicles meet the exhaust emission standard due to the regulation effects at the outset. However, there are few regulations after the registration and before the renewal inspection. Goods vehicles and the like are put under heavy load when gathering speed with a full load. Moreover, black smoke (PM) in the exhaust gas emitted during the drive where start and stop are repeated increases proportional to a travel distance under the present conditions. A black smoke measurement device or opacimeter is used to measure exhaust gas in the vehicle renewal inspection. The most important issue is the emission of black smoke (PM) in the practice of the inspection.
In order to solve such a problem, new technologies have also been developed. Specifically, fuel is injected a plurality of times by a common rail system that injects fuel at high pressures, and electronic control, so that complete combustion is promoted. Particulate matter (PM) is filtered using a particulate matter removing device (DPF: diesel particulate filter). The particulate matter is burned to form CO2. Furthermore, a urea injection system (SCR selective catalytic reduction) is used to convert harmful NOx into harmless nitrogen and water. Consequently, the gas emitted from the engine is harmless CO2, nitrogen, and water. In order to reduce them simultaneously, an ultra high pressure common rail fuel injection system, a urea SCR (selective catalytic reduction) system, a particulate matter removing device, and the like are mounted. Consequently, the above simultaneous reduction is achieved. The latest diesel engine can meet the NOx and PM emission standard during a period while the new-vehicle state can be kept. However, there is a problem that the vehicles with a long use period and a long travel distance and the vehicles before the regulation may not meet the standard at the time of the vehicle renewal inspection.
Effective means for reducing black smoke and the like that are emitted from existing diesel vehicles no matter how small a degree is to use the engine with a clean inside by keeping the new-vehicle state as much as possible, or to create an environment in which complete combustion can be achieved by cleanly removing carbon and sludge deposits and the like on the intake and exhaust systems and the combustion chamber. In the gasoline engine, a cleaning agent such as a solvent can be mixed in an air/fuel mixture with the engine running Hence, it is relatively easy to clean the inside without dismantling the engine. Hence, various commercial cleaning agents for the gasoline engine are available. However, the diesel engine has difficulty performing a practice similar to that performed by the gasoline engine. In other words, the diesel engine does not have an ignition system, and accordingly causes fuel to be spontaneously ignited by compression heat, and burns the fuel. Hence, a combustible material taken into the cylinder in the intake stroke with the engine running, the combustible material having a lower ignition temperature than that of diesel fuel such as light oil, is self-ignited in the compression stroke. Hence, what is called diesel knock occurs, and accordingly the engine is broken. For this phenomenon, a method for diluting the concentration of an internal cleaning agent for a diesel engine to approximately 1% is conventionally taken when the cleaning agent is mixed with the fuel for use.
However, strongly adhering or deposited carbon and sludge cannot be removed completely with such a conventional fuel mixing type cleaning agent. For example, cleaning work may be performed using a fuel mixing type cleaning agent having a high cleaning effect due to a chemical action. This cleaning agent contains a surfactant mainly including alkyl amine oxide, an inorganic alkali agent, an amine solvent, a glycol ether solvent, and the like. Hence, there is a problem of the aftertreatment of the used strong alkali agent. Moreover, the evaporation of acetone or thinners during work also has an adverse effect on the natural environment and the health of the worker. Hence, it is desired to avoid their use. Furthermore, if the engine is dismantled for the work, the amount of use of the strong alkali agent and acetone or thinners is several liters. On the other hand, in the method of spraying inside the engine, the required amount of use is several hundred milliliters. Therefore, the use of an approximately 10-times amount is required in the case of overhauling. Hence, the influence on the natural environment is further increased. In any case, if a diesel engine mounted vehicle finds its state as bad as that it cannot pass the renewal inspection, for example, the following means is taken. Chemical cleaning is performed in which a surfactant and a solvent of amine or the like are attached and penetrated to the dismantled engine for dissolution. If hard carbon that is out of control in the chemical cleaning deposits, means for applying physical stress such as polishing work and separating the hard carbon, or replacement with a new part or rebuilt engine is performed. They have a problem that it takes trouble, time, and costs.
In view of the above circumstances, various technologies have conventionally been proposed. Proposed is, for example, “in a cleaning method where a cleaning agent is injected into an intake manifold of an automobile diesel engine to clean an intake system and a combustion chamber, a method for cleaning the intake system and the combustion chamber of an automobile engine is provided, where an air duct provided between an intake manifold and an air cleaner is removed from the intake manifold, and the cleaning agent is injected toward the inside of the intake manifold in a fine mist form with such a spread as to spread evenly inside the intake manifold when the engine is running” (see Patent Document 1).
The above technology relates to the following technology. In other words, as means for avoiding diesel knock, a nozzle, called mechanical brake-up tip, that makes the cleaning solution finer is provided to a distal end of a tubular-shaped nozzle, liquid particles in an atomized state are made finer, and the amount of the cleaning solution is reduced. Accordingly, diesel knock and water hammer are avoided. The above technology, similar to the invention of the present application, cleans the intake system to the inside of the combustion chamber without dismantling and cleaning the diesel engine when the engine is running.
However, according to such a technology, it is required to reduce the injection amount of the cleaning agent. Therefore, an effective cleaning effect cannot be obtained. Hence, it is not suitable to remove strongly deposited carbon. Moreover, in the technology, there is neither description nor suggestion to specify the composition of the cleaning agent. Hence, conversely, the atomization of fine particles makes it easy to cause abnormal combustion being early self-ignition in the compression stroke, depending on the kind of cleaning solution. Moreover, in Patent Document 1, the injection time is 96 ml, 6.5-7.5 ml/10 sec, 2 minutes 28 seconds to 2 minutes 8 seconds. Therefore, this is different from a method of the invention of the present application that gradually removes accumulated carbon and combustion waste over 20 to 30 minutes, using the penetration ability of the cleaning agent and the intake pulse and combustion pressure by the operation of the engine.
Moreover, an “aerosol product for cleaning a diesel engine intake system and a cleaning method using the same, which can clean the intake system excellently without dismantling a diesel engine, and also reduces an abnormal high rotation speed of the diesel engine and knocking” is also proposed (see Patent Document 2).
In such a technology, a main technology to avoid knocking is a cleaning agent injection amount per unit time as described in claim 1 according to Patent Document 2. An injection amount in a common range to an injection amount recommended by the invention of the present application is described therein. In Patent Document 2, there is a description of 6-3 g/10 sec, but an absolute injection amount is not described. The amount of a cleaning agent according to the difference of engine displacement is not written. Patent Document 2 and the invention of the present application are very different in the following points. In other words, the invention of the present application requires an approximately half injection amount of 5-20 g/min (0.83-3.3 g/10 sec) compared with the invention of Patent Document 2. Furthermore, evaporation time is taken into account in the case of the cleaning agent of the invention of the present application. Moreover, Patent Document 2 also describes that the characteristics of an aromatic solvent, such as a flash point, are taken into account to avoid knocking.
Furthermore, the injection amount of the present application is 0.5-1.0 g per 1 cm2 of the area of the combustion chamber for 20 to 30 minutes. A description of such an amount of the cleaning agent according to the area of dirt is not found, either.
However, the aromatic solvent concretely specified in the above technology has a lower flash point than that of light oil. Hence, as can be seen from the embodiments described in Patent Document 2, knocking is more likely to occur. Hence, the absolute amount of the solvent cannot be increased. Moreover, many of aromatic solvents are more likely to evaporate under high temperature conditions. Hence, the solvents evaporate and burn off before penetrating gaps between carbon deposit layers. Hence, strongly deposited carbon layers cannot be separated. Hence, the above technology cannot use the physical action of a flame shock as in the invention of the present application.
Furthermore, a technology of “a cleaning agent composition which is suitable for an oil fouling removal process by exerting excellent oil fouling cleaning performance without having an adverse effect on a base material, and the like, and further suitably used for cleaning an engine compartment, cleaning tools and parts, and cleaning a floor” is also proposed (see Patent Document 3).
In the above technology, a surfactant with alkyl amine oxide as the main component, and an inorganic alkali agent are contained. Alternatively, alkyl amine oxide, an inorganic alkali agent, and an amine solvent and/or glycol ether solvent are contained. Therefore, a cleaning effect by the chemical action is estimated to be high. However, the surfactant is the main component, and accordingly, the environmental load is heavy. Moreover, the technology is conceived on the precondition that the engine is dismantled and cleaned. Hence, it is considered that the technology cannot be used when the engine is running. Moreover, it is desired to avoid aftertreatment of the strong alkali agent used for the cleaning work and evaporation of acetone or thinners during work. This point is similar to white exhaust smoke or one providing stimulation to a person that is emitted in the conventional method that injects a cleaning agent into the engine for cleaning. In the case where the engine is dismantled to conduct work, the amount of use of these strong alkali agent, and acetone or thinners is several liters. On the other hand, the method in which the inside of the engine is sprayed requires the amount of use of several hundred milliliters. Therefore, the use of an approximately 10-times amount is required in the case of overhauling. Hence, the influence on the natural environment is also increased.
An acetate solvent, an amine alcohol solvent, ammonia water, ethers, esters, glycol ether, ketones, terpene alcohol, terpene hydrocarbon, a chlorine compound (halogen), a surfactant, a nitrogen compound, fatty acid, a petroleum solvent, and the like have been used as conventional solvents for the purpose of cleaning the inside of the engine. They also contain the target solvents of harmful substances whose names and the like should be notified under the Industrial Safety and Health Act, the Act on the Evaluation of Chemical Substances and Regulation of Their Manufacture, the Poisonous and Deleterious Substances Control Law, and the Act on Confirmation, etc. of Release Amounts of Specific Chemical Substances in the Environment and Promotion of Improvements to the Management Thereof (PRTR Law). The use of these solvents is desired to be avoided as much as possible.
Moreover, many of solvents used for commercial cleaning agents have IPA (isopropyl alcohol) or MEK (methyl ethyl ketone) as the main component. The cleaning effects of such solvents are worthy of evaluation. However, volatility is extremely high, and hence a problem that the health of the worker is impaired, such as causing the irritation of the eyes of the worker or causing breathing difficulty, arises if used with the engine running.
Moreover, the commercial products used with the engine running include, for example, a trade name: Throttle Valve Cleaner (product number/code: A110 TV-C) of WAKO Chemical, Ltd. However, as described in the precautions for use, diesel knock occurs if used for the diesel engine. For this reason, it is instructed not to use the product when the engine is running and to be sure to stop the engine and clean with a brush. Moreover, the company also has a system, a trade name: “RECS (rex),” that injects a cleaning agent during the operation of the engine (configured by the cleaning agent and a syringe using engine vacuum). However, this system emits a large amount of white exhaust gas during and after the injection of the cleaning agent. Moreover, the system cannot be used for the diesel engine.
The inventor of the present application has performed overhauling work for the purpose of repair and output improvement on race engines and commercial engines, and the like over the long period. In these experiences, the inventor also handled many engines that had been used without replacing oil for a period twice or more as long as a normal oil replacement period, and engines of vehicles that had traveled with an oil amount less than specified. What the inventor noticed through such experiences gives a clue to the present invention. In other words, a considerable amount of carbon and sludge may be attached in the vicinity of the center of the top of the piston in an engine under severe conditions or an engine whose lubrication condition has grossly deteriorated. Even in such a case, it is confirmed in many cases that carbon and sludge were removed from the vicinity of the top of the piston and an area called piston round, and the metal surface of the piston was exposed. In other words, attention is given to a point that the lubricating oil that have entered the combustion chamber in an oil rising phenomenon due to the wear of the piston, cylinder, and piston ring also has a high cleaning effect. In addition, an inspiration is formed in which the forces of pulsations and combustion waves that are generated by the engine are also more effectively used, and accordingly the inside of the engine can be cleaned more efficiently without emitting toxic substances. Experiments were performed from many different angles for blending conditions of a solvent and grease that do not cause diesel knock, and the like, and combustion state, evaporation time, and the like of a cleaning agent. As a consequence, a cleaning agent according to the present invention that can also clean a diesel engine with the engine running, similarly to the cleaning of a gasoline engine, has been developed. Various experiments were repeated on a point that which system makes the use of the cleaning agent most effective to enhance the effect of the cleaning agent. As a consequence, a cleaning system according to the present invention has been completed.